T3 Rev WS5
Setting
Up
Algebraic
Equations
In each of the followings, let x denotes the
unknown. Derive an equation involving x.
Q1) When a certain number is increased by
7, the result is 18.
x + 7 = 18
When
a
number
is
decreased
by
2
and
Q2)
the result multiplied by 3, the final result
is 24.
3(x – 2) = 24
Q3)
When a certain number is subtracted from
24 and the result divided by 5, the final
result is 4.
24  x
4
5
Q4)
The sum of three consecutive numbers is
63.
Let the first number be x,
x + (x + 1) + (x + 2) = 63
Q5)
Six times of a certain number is 16 more
than twice the number.
6x = 16 + 2x
Q6)
The length of a rectangle is twice its width
and the perimeter is 54 m.
Let the width = x m
2(2x + x) = 54
Q7)
Peter has five times as much money as
David. If Peter gives $28 to David, both of
them will have equal amounts of money.
How much money did Peter have at the
beginning?
Let the amt David has at the beginning = $x
 Amt Peter has at the beginning = $5x
5x – 28 = x + 28
… (DIY) … x = 14
Peter has $70 in the beginning.
Q8)
There are a total of 225 pupils in
Secondary one. If the number of pupils
who pay their school fees through GIRO
scheme is 14 times the number of pupils
who do not, find the number of pupils
who did not join the scheme.
Q8)
There are a total of 225 pupils in Secondary one. If the
number of pupils who pay their school fees through
GIRO scheme is 14 times the number of pupils who do
not, find the number of pupils who did not join the
scheme.
Let the no. of pupils who did not join GIRO
scheme = x
 No. of pupils who join GIRO scheme = 225 – x
225 – x = 14x
… (DIY) … x = 15
 15 pupils did not join the GIRO scheme
Q9)
$4800 is divided among three brothers A, B
and C. A receives three times as much as B
and C receives twice as much as B. If B
receives $x, form an equation in x.
Amt B receives = $x
 Amt A receives = $3x
& Amt C receives = $2x
The required equation is
3x + x + 2x = 4800
Q10)
Three wallets and two handbags cost $450
and a handbag costs twice as much as a
wallet. If a wallet costs $x, form an equation
in x.
Given that the cost of a wallet = $x
 The cost of a handbag = $2x
The required equation is
3x + 2(2x) = 450